1. Field of the Invention
The invention relates to a vehicle information acquisition system and a vehicle information acquisition method that acquire pieces of vehicle information from an information processing unit mounted on a vehicle.
2. Description of Related Art
In general, a vehicle such as an automobile or the like is provided with a self-diagnosis unit that diagnoses a vehicle state including a state of an internal combustion engine and the like based on pieces of vehicle information acquired from various sensors that are mounted on the vehicle. Such a self-diagnosis unit can carry out a more detailed diagnosis and a more accurate diagnosis as the number of pieces of vehicle information to be used for the diagnosis increases. On the other hand, the increase in the number of pieces of vehicle information to be used for the diagnosis leads to an increase in the load in processing those pieces of information and the shortage of a storage area as well, so that the determination of a cause at an appropriate timing may be made difficult as a result of a fall in the processing speed of the self-diagnosis.
Thus, an example of a system that can restrain the processing speed of a diagnosis processing from falling while maintaining a certain diagnosis accuracy is described in Japanese Patent Application Publication No. 2005-146905 (JP 2005-146905 A). In the system described in JP 2005-146905 A, a piece of information on a failure in a target region of a failure diagnosis is detected as a piece of diagnostic information, and a piece of failure history information on the target region (a piece of vehicle information) is transmitted from a vehicle to a dealer. Then, after receiving the piece of the failure history information (the piece of the vehicle information) thus transmitted from the vehicle, the dealer identifies this vehicle based on a result of an analysis of the piece of the failure history information, and makes a transmission request to request this identified vehicle to transmit the piece of the diagnostic information. In this system, as described above, the piece of the diagnostic information to be used for the failure diagnosis is selected from the piece of the failure history information (the piece of the vehicle information) on the dealer side. Thus, the load in processing pieces of information by the self-diagnosis unit on the vehicle side is alleviated, and the piece of the diagnostic information to be acquired is narrowed down on the dealer side as well, so that the processing load of the diagnostic processing is restrained from increasing. Besides, since the diagnostic processing is performed based on the narrowed-down piece of the diagnostic information, the diagnostic accuracy thereof can be held high.
By the way, in recent years, a vehicle is equipped with a large number of information processing units such as various electronic control units (ECUs) and the like, and programs that are executed and processed by those information processing units are also becoming the target of a self-diagnosis. Besides, the self-diagnosis in this case is different from a method of identifying an already-prepared piece of diagnostic information by narrowing it down from a piece of failure history information (a piece of vehicle information) as in the case of the system described in JP 2005-146905 A, and often adopts a method of identifying an origin of a piece of vehicle information that assumes an abnormal value by tracing back the processing procedure of a program. However, the preliminary embedment of positions for acquiring those pieces of vehicle information for determining a cause in the program that is used to determine the cause incurs the complication of the program itself, and hence is not easy. Further, even if such a program can be created, an attempt to enhance the diagnostic accuracy thereof cannot avoid an increase in the number of pieces of vehicle information to be used for the diagnosis.